Middle Income Wage Earner Tax Relief Act of 1980

Middle-Income Wage Earner Tax Relief Act of 1980 - Title I: Four Percent Income Tax Credit for Individuals - Amends the Internal Revenue Code to allow a refundable income tax credit equal to four percent of the taxes paid by individual taxpayers. Limits the amount of such credit to $250 for the taxable year for a taxpayer filing an individual return and $500 for the taxable year for taxpayers filing a joint return. Disallows such credit to any estate, trust, or nonresident alien individual.

Title II: Permanent Tax Credit for Social Security Taxes - Amend the Internal Revenue Code to allow a refundable income tax credit equal to ten percent of the net social security taxes paid by employees, employers, and self-employed individuals during the taxable year.

Title III: Relief from Marriage Penalty - Amends the Internal Revenue Code to allow married individuals filing jointly a nonrefundable income tax credit equal to six percent of the earned income of the spouse who earns 50 percent or less of the combined earned income of both the husband and wife for the taxable year. Limits the amount of such credit to $500 for the taxable year. Requires the reduction of such credit by one percent for each percentage point by which the lower income spouse's earned income is below 30 percent of the couple's combined earned income.

Title IV: 10-5-3 Capital Cost Recovery - Amends the Internal Revenue Code to revise the method for determining useful lives of business assets for purposes of computing allowable depreciation deductions. Replaces the asset depreciation range (ADR) method with a schedule of capital cost recovery periods for three classes of business property.

Establishes capital cost recovery periods for the following classes of business property: (1) buildings and their structural components, ten years; (2) tangible property, five years; and (3) automobiles, taxis, and light-duty trucks (up to $100,000), three-years. Allows a ten percent investment tax credit for buildings and tangible property, and a six percent credit for automobiles, taxis, and light duty trucks. Requires the recapture of depreciation amounts and investment tax credit amounts applicable to assets which are sold or otherwise disposed of prior to the expiration of the capital cost recovery period. Permits a taxpayer to deduct less than the full allowance for capital cost recovery in any taxable year. Permits a carryover to succeeding taxable years of any unused depreciation amounts.

Disqualifies capital cost recovery property from the allowance for first year depreciation.

Treats amounts claimed as the capital cost recovery of noncorporate lessors as an item of tax preference for purposes of the minimum tax.

Adopts as an accounting practice the "half year convention" under which investments eligible for capital cost recovery treatment or the investment tax credit which are made at any time during the taxable year are deemed to be made in the middle of such year.